925合金在饱和H_2S盐水中的腐蚀电化学特征  

Electrochemical Characteristics of Alloy 925 in Aqueous Solution Containing Saturated H_2S and Salt

作　　者：王春光[1] 王东哲[1] 万红[1] 刘微[2] 黄国平[1] 刘海定[1] 欧文永[1] 葛锋[1] 

机构地区：[1]重庆材料研究院有限公司国家仪表功能材料研究中心,重庆400707 [2]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《石油化工腐蚀与防护》2014年第5期6-9,共4页Corrosion & Protection In Petrochemical Industry

基　　金：国家"863计划"科技攻关项目(项目编号:2013AA031005);重庆材料研究院青年基金项目(项目编号:13091032)

摘　　要：利用塔菲尔(Tafel)极化曲线测试方法和电化学阻抗(EIS)测试方法,研究了镍基合金925在饱和H2S盐水环境下腐蚀过程不同时段的电化学行为。结果表明:在饱和H2S盐水作用下,试验开始至第9 d时腐蚀电位一直在降低,最低-418 m V,随后腐蚀电位逐渐升高,第17 d时腐蚀电位达-301 m V,而腐蚀电流在第5 d之前降低至1.2μA,第9 d升高至2.57μA,之后一直降低1.55μA。电化学阻抗谱显示高频区的容抗弧越来越小,扩散特征增强,可能是形成的腐蚀钝化膜不够致密。综合分析认为试验进行5 d后原有的氧化膜破坏,开始形成新的保护膜,9 d后合金钝化效果明显,合金耐腐蚀性增强。Electrochemical behaviors of nickel - based alloy 925 in aqueous solution containing saturated H2S and NaC1 were studied by Tafel polarization and electrochemical impedance spectroscopy （EIS）. The results showed that, in saturated H2S and salt environment, the Ecorr remained low before 9th day and the minimum is -418 mV. Then it began to increase gradually and rose to -301 mV at the 17th day. Whereas, the Icorr deereasd to 1.2 μA before 5th day and then rose up to the maximum 2.57 μA at 9th day. After that, it gradually went down to 1.55 μA. EIS measurement indicates that capacitance loop becomes increasingly smaller and diffusion characteristics are enhanced. It is possible that the passive film is not compact enough. The original oxide film is broken before 5th day, and a new protective film began to be formed. The passivation is obvious after 9 days, and the corrosion resistance of alloy 925 is improved.

关 键 词：925合金 H2S NACL 电化学阻抗谱 钝化膜 

分 类 号：TE983[石油与天然气工程—石油机械设备]